Metal drawing apparatus



April 29, 1947.

R. W. ANDREWS, JR, ET AL METAL DRAWING APPARATUS Original Filed Aug. 3,1939 5 Sheets-Sheet l M 5 R w m V m Ray/ml M Andrews, J7.-

QW'EORNEY Ap i 29, 1947. R. w. ANDREWS, JR., ETAL 2,419,870

METAL DRAWING APPARATUS 3 Sheets-Sheet 2 Original Filed Aug. 3, 1939 IIIall! I! III lll mvu-rons MAndmmgi at Arthur 731781151.

ATTORNEY April 1947. R. ANDREWS, JR, ET AL 2,419,870

METAL DRAWING APPARATUS Original Filed Aug. 5, 1959 3 Sheets-Sheet 3INVENTORS Raynai w. AndrewgJr. amy Ar-Mur 71' Daily ATTORNEY PatentedApr. 29, 1947 2,419,870 METAL DRAWING APPARATUS Raynal W. Andrews, Jr.,New Kensin'gton, and Arthur T. Deily, Pittsburgh, Pa., assignors toAluminum Company of America, Pittsburgh, -Pa., a corporation ofPennsylvania Original application August 3, 1939, Serial No.

288,163, now Patent No. 2,331,953, dated October 19, 1943. Divided andthis application June 21, 1940, Serial No. 341,697

This application is a division of our application Serial No. 288,163,filed August 3, 1939, now Patent No. 2,331,953, issued Oct. 19, 1943,for improvements in Metal working apparatus, and

relates particularly to control of the drivingv means and to means forattaching a carriage thereto in a metal drawing apparatus. Ourapplication, Serial No. 341,696, filed June 21, 1940, for improvementsin Carriage for metal drawing apparatus is also a division of ourabove-mentioned application.

This invention relates to apparatus for working metal shapes, and moreparticularly to draw benches for drawing tubular shapes, rods and thelike through a die.

The usual draw bench for tube drawing comprises a supporting frame orframes upon which are mounted a die, a mandrel and bulb, a draw chain orthe like, and a carriage having jaws for gripping the work after it hasbeen passed over the mandrel and bulb and inserted through the die. Thecarriage must be moved to draw the work through the die, and for thismotion generally engages with, and receives its drawing force from, adraw chain or similar device.

It has been customary for draw chains to be driven continuously and atconstant speeds; and it has further been customary for a carriage to beengaged with the chain while it is in motion at such constant speed,thus accelerating the work almost instantaneously.

The jerking and shock of such rapid acceleration of the work frequentlycauses breakage in the work and results in waste of material and loss ofuseful production time. A further cause of breakage, waste, and poorwork has been the fact that the gripping jaws of the drawing carriagesof prior apparatus have not been designed to engage the work at pointsother than along the axis of the draw, and work-pieces pointed forengagement by the jaws often have pointed ends which are bent ofi centeror otherwise disposed out of alignment with their normal axes;

Also informer practices, production has been limited by the timerequired for the return of the drawing carriage to the die head and bythe time required for passing new work over a mandrel rod and bulb. I

The general object of this invention is to improve the drawing devicesof the prior artto produce draw benches or similar apparatus in whichthe drawing operation may be performed with less loss of usefulproduction time and less wastage of material than is now usuallyobtained. Specifically, this general object is obtained, in

i Claim. (01. 205-3) z whole or in part, by the realization, singly orcombination, of the following more specific obects: The provision in adraw bench 011 a variable speed draw chain which may be stopped orslowed perceptibly, as the jaws clamp the work, for engagement therewithof the hook supported by the drawing carriage. The provision of a powersource actuating such draw chain which is capable of quickly and evenlybringing the work up to a relatively high drawing speed without undueshock. The provision of means for automatically K reducingv the speed ofsaid draw chain and stopping the drawing carriage upon completion of adrawing operation. The provision of a draw chain assembly which willuniformly transmitdrawing energy from the power source to the workpiecewith a minimum of variation in actual drawing speed. The provision in adrawing carriage of work-engaging Jaws adapted to engage such portionsof the work-piece as may be located out of the axis of the draw, and ofjaw-actuating means adapted to this purpose. The provision of a systemor means capable of accelerating and decelerating the drawing carriageduring its movement on return to the die head after the completion of adrawing cycle, and the provision of such a system or means capable ofactuating said car riage without undue shock.

These and further objects and advantages of this invention, eithersingly or in combination, are for purposes of convenience illustratedwith respect to a specific mechanism which embodies all of the specificfeatures of the invention. It will be understood, however, that thesefeatures may be available for single use, or in any suitablecombination, to improve the operation of draw benches or similarapparatus which do not include all of said features.

'In the drawings:

Fig. 1 is a partial plan view of the preferred form of a mechanismembodying the features of the invention, and showing two mandrel rods,

the die head, the drawing carriage, the draw engaging hook is in alowered position, in its first engagement with the draw chain;

Fig. 4 is a fragmentary view, partly in section, of the jaw-actuatingcrank, Jaw-actuating levers, and associated parts, taken along the lineIV-iV of Fig. 3, the crank and levers being rotated into verticalposition for simplicity of illustration;

Fig. is a plan view of the drawing carriage shown in Fig. 3, and to thesame enlarged scale, in which one-half is a section taken as indicatedby the reference line V-V of Fig. 4.

Briefly, the apparatus as shown comprises a draw bench frame, a drawinghead or carriage, a drawing die, and two work supporting mandrels. Ahollow shape may be passed over one mandrel within a protecting shell orother guiding support by hand or by suitable mechanical loadingmechanism (not shown); the mandrels may be'rotated to align onework-piece and mandrel with the die; the.point of the work-piece may beinserted through the die; and the mandrel and work-piece may be forcedinto registry with the die conjunctive with the beginning of the drawingaction. The drawing carriage and its work gripping jaws may be actuatedto clamp the point of the hollow-shaped work-piece, and may be movedalong the draw bench by suitable engagement with a draw chain to drawthe workpiece through the die. Upon completion of a draw, the work-piecemay be released to aconvenient rack or removal apparatus (not shown).

Endless return means are provided for automatically traversing thedrawing carriage back to the die head after completion of a drawingoperation. Such endless return means are preferably operableindependently of the drawing chain and preferably are adapted to controlthe position and rate of speed of the drawing carriage during its returnmovement.

As will appear more fully in the detailed description of the apparatusas shown, means have been provided throughout for automatic operation ofthe draw bench during at least one complete drawing cycle.

Die section The die section of the draw bench will now be described withspecial reference to Figs. 1 and 2 of the drawings. By the die sectionis meant that portion of the apparatus immediately adjacent, orassociated with, the drawing die. A main piece. Bulbs II and i3 aresecured to mandrel rods l0 and I2, respectively, by suitable threadednuts l4, preferably tapered outwardly to facilitate passing of tubularand hollow-shaped stock thereover.

Means not necessarily forming part of this invention may be provided forplacing a workpiece on the mandrel when it is in the position of mandrell2. Means may be provided for rotatframe I is secured on foundation 2;and at one end of the main frame (to the left as viewed in Figs. 1 and2) is mounted a removable die head 3, incorporating drawing die 4, dieretaining block 5, and retaining pin 3. The die 4 is removably mountedto facilitate change or replacement of dies to take care of differentsizes and shapes of material to be drawn. The die head 3 may be removedfrom the frame by engagement of acrane hook with an eye -bolt I. The diehead may be suitably shimmed for alignment about the axis of draw in oneor more planes, or a tilting die head, adjustable about either verticalor horizontal axes, can be employed if desired.

The work-piece, here a tube 8, is shown with its pointed end 3 insertedthrough die 4. As shown in the sectioned portion of Fig. 2, the drawingoperation has not started, and, therefore, mandrel rod Ill and bulb iiare not shown in full registry with I I2 and bulb [3, are located aboveand behind mandrel rod Ill and bulb ll. Said second mandie 4. A secondmandrel rod ing the mandrel rods to bring the mandrel rod and work-piecefrom the position of mandrel rod l2 to the lateral position of mandrelrod iii; and means may be provided for advancing a mandrel rod and itswork-piece to the die to occupy the position of mandrel rod l0, bulb II,and tubular work-piece 8, as shown.

Means are provided for protecting and supporting a work-piece passedover a mandrel rod and bulb. These means preferably take the form oftubular shells 18 supported at convenient intervals along their lengthby mandrel supports 24 (one of which is shown to best advantage in Fig.2) comprising bases 25 attached to foundation 2. Adjacent die head 3suitable bellmouthed guide bushings l8 are mounted within end portionsof shells IE to facilitate the entry of a hollow shape over a mandrelrod and within the protective and supporting shell. Looking bands 20',adapted to compress tubular shells I. on bushings l8, may be readilyloosened for interchange of bushings of various size depending on thesize of tube to be drawn, With respect to the mandrel rod, bulb, andhollow-shaped work-piece, each guide bushing is arranged to partiallysupport the work-piece at a point adjacent the die head when the bulb isforced into registry with the die by means of the mandrel rod.Additional guide bushings 22 are located at suitable intervals withinthe shells l6 and provide further points of support for the work-piece.Tubular shells iii are designed to protect the work against scratchingand dirt and, with bushings l8 and 22, to support work of considerablelength. Where protection of the work from dirt is not a primary problem,the shells 13 may take the form of spaced sections or rings rather thancontinuous lengths of tubing as shown.

Drawing section Referring to the drawings, the drawing section of thedraw bench is now described. This section of the bench is defined asthat portion of the bench, including the associated apparatus, overwhich the stock is pulled or drawn 'from the die I. The drawing sectioncomprises generally frame I, draw head 30, and tracks or rails 3i alongwhich the carriage may move on carriage wheels 32. Gripping jaws 33 and34 are located in draw head 30 and are adapted to engage the pointed end9 of the tubular work-piece 3. Carriage hook 35 is adapted to engageendless draw chain 36. A pair of suitable return .chains or otherendless driving means 31 and 23 are connected to carriage 30 on either.side thereof and adapted to return the carriage to die head 3 uponcompletion of a drawing operation.

Means are provided upon carriage Ill, here in the form of trip arm 39,for actuating a plurality of limit switches 40, ll, 42, 43. 44, and II,which are located along the main frame I, as shown. These limit switchesare arranged to control acceleration and deceleration of drawingcarriage 30 during its forward drawing and return movements, and furtherto control various other operations to be hereinafter described.

Draw chain 36 is centrally located within frame I and is supported overdrive sprocket 46 and idler sprocket 41. Drive sprocket 46 is preferablydriven by either one or both of two m otors (preferably hydraulic, butnot shown) connected to a drive coupling 48 at the extreme forward endof the bench (to the right as viewed in Figs. 1 and 2), which drivecoupling 48 is connected to the draw chain drive sprocket 46 through adrive shaft 49 held in frame I by bearings 50 and 5|. The draw chain maybe lubricated by continuous immersion in a suitable oil reservoirlocated in the path of the under portion of the chain, but not hereshown. The idler sprocket I1 is located adjacent the die end of frame Iand is mounted on an idle shaft 52 journalled in adjustable bearings 53.These bearings may be moved longitudinally of the draw bench by means ofnuts 54 on screw threaded rods 55, for adjustment of the draw chaintension or for removal of the draw chain.

The draw chain 36 has preferably a short pitch, that is, the links aremade as short as possible so that variation in linear velocity of thechain will be kept at a minimum; and the drive motors for the drawingchain preferably have rigid speed control so as to produce as nearlyconstant drawing velocities as are feasible. By means of this preferredform of apparatus, the drawing speed may be varied from practically astop up to normal speed, under no load up to heavy drawing load, withrapid and even acceleration, initiated by electrical control operablethrough limit switch 43.

Return chains 31 and 38 are fixed to carriage 30, through tie plates 56,and,are supported and located on either side of frame I, being engagedby drive sprockets 51 adjacent the die end of said frame and by idlesprockets 58 at the opposite end of said frame. Drive sprockets 51 aremounted on a common drive shaft 59, which carries belt pulley orsprocket 50, and is journalled in suitable bearings 6|. The drive shaftand sprockets are driven by electric motor 52 through drive belt orendless chain '53 and belt pulley or sprocket 60. The return chain idlesprockets 58 are located on common idle shaft 54 joumalled in adjustablebearings 55. Means for adjusting the tension of return chains and forpermitting their ready removal are here provided in the form of threadedrods 55 and adjusting nuts 51 provided thereon. Return chains 31 and 38are recessed in chain guards 58 for protection of both chains cam 59(Fig. 2) located adjacent the die head of the drawing section of thedraw bench, or of stop cam .10 located at the other extremity of thedraw'bench. At either cam the action of release lever 1| and its roller12 is to lift hook 35 out of engagement with drawing chain 36, therebybringing carriage to rest.

Cam 69 is provided for the purpose of releasin the carriage hook fromthe draw chain when the carriage jaws have failed to engage theworkpiece or in case of breakage of the work-piece during forward travelof carriage 30. In either event, there is no drawing tension onthechaiu.

and operator. Suitable means may be provided for lubricating such chainswhere desirable. The electric motor 52 operating said return chains ispreferably adapted to be used as an a electric brake upon the drawcarriage 30 as it approaches the die head 3. In this way the movement ofthe carriage on its return to the die head is positively controlled,thus eliminating the If the carriage 30 has engaged work-piece 8 throughthe proper clamping engagement of jaws 33and 34 upon the work, thedrawing tension exerted on draw chain 35 will lift the chain and theengaging carriage hook 35-sufliciently 'high to permit hook releaselever II and roller 12 to clear the cam 69. Thus the normal drawingoperation will continue until the work-piece is free of drawing die 4.At this point, drawing tension is immediately released and the drawchain tends to fall and disengage itself from the hook 35. Cam 10functions as a safety device and hook adjusting mechanism in the eventthat hook 35 does not, at the end of the drawing operation and whendrawing tension is released, release itself from the chain but fallstherewith. In such case, the release .lever 1| and its cam follower 12contact cam 10, with the result that the hook 35 is positively raisedand disengaged from the chain 33, and reset in its raised posi- I tion,thus preventing the continuously traveling .chain 35 from dragging thedraw head 30 off the end of the bench, or preventing other injury to theassembly.

Draw head With reference especially to Figs. 3 through 5, the draw heador carriage 30 will now be particularly described. In the carriage arethe aforev work-piece at the die head 3. These jaws are so necessity foremploying previously used shock absorbers or cushioning devices to stopthe carriage at the die head. The two return chains 31, 38 arepreferably provided to insure align ment of the drawing carriage withthe die head upon its approach thereto,'but a single chain or cable maybe used with satisfactory results. The acceleration and deceleration ofthe drawing carriage 30 on its return travel may be accuratelycontrolled through one or more of the aforementioned limit switches," ashere shown by switches 40, II, and 42, which switches are actu-J 1 isarcuate in form (see Fig. 2) to conform with ated by the drawingcarriage trip arm 39. I

Other elements of the drawing section of the arranged that one jaw mayadvance or adjust itself relative to the other, and relative to thework-piece to grip the pointed end 8 thereof and exert an axial drawingforce thereon despite any irregular formation or non-axial alignment ofsaid work-piece end. Further it may be noted that the jaws are actuatedthrough a, linkage,v

which will be described hereinafter, by means of the forces exerted bythe draw chain engaging hook 35.

The carriage or draw head 30 is provided with a transverse shaft 15journalled in the frame thereof. Centrally on said shaft is keyed theolevised end (see Fig. 5) of carriage hook 35. Thishook has alink-engaging portion 16 which a link of the draw chain, the saidarcuate portion 'draw bench which should be noted at this point beingpreferably adapted to engage somewhat chain 35 on the 7 more than 90 ofare on any particular link. Also keyed to shaft 15, at one end thereof,and located outside the frame of carriage 38, is the hook release lever1| and its cam contacting roller" 12. The keyed angular relationship ofhook 35 and hook release lever H on through shaft 15 is such that whenlever 1| is in its lower position, its roller 12 would engage cam 69 orstop cam 18, on approach thereto, and rise thereon, thereby raising hook35.

Also keyed to shaft 15 between forked portions of the clevised end ofhook 35 is a crank lever 11 extending in a generally vertical directionabove top plate 18 of carriage 38, said hook 35 and crank lever 11substantially forming a bell crank oscillatable with said shaft 15, inaccordance with the forces imparted to the hook by means of the drawchain 36, or to the hook release lever 1| by means of the cams 69 or 18.

Disposed laterally and approximately centrally of carriage 38, above topplate 18, is pin 19 supported and retained in bearing blocks 88, 8|.oscillatable on pin 19 is a centrally disposed crank 82 which extendsupwardly therefrom in a generally vertical direction. Adjustable link 83connects the upper extremities of crank 82 to crank lever 11, wherebycrank lever 11, adjustable link 83, and crank arm 82 form, with theframe of the carriage, a quadric-crank linkage.

Preferably integrally formed with the lower portion of crank 82 is aprojection forming a latch 84 adapted to be engaged by pawl 85, wherebythe quadric-crank linkage actuated by hook 35 or release lever 1| may belatched with the hook in its raised position in a manner which will bemore fully described hereinafter.

Also oscillatably mounted on pin 19, on either side of crank 82, arejaw-actuating levers 86 and 81, which levers have portions extending ina I generally vertical direction above pin 18 in normally parallelrelationship with crank arm 82, and jaw-actuatin portions extendingbelow pin 18 to act as lever arms. Jaw-actuating levers 86 and 81 areindependently oscillatable On pin 18 and are inter-related in theiraction by a doubleacting spring 88 and associated parts. At the lowerextremities of said jaw-actuating levers are adjustable links 89 and 98connecting to workengaging jaws 33 and 34, respectively. Said jaws areslidable on converging ways 9I (see Fig. The latterly described portionof the actuating linkage for each jaw may be referred to as aslider-crank linkage, said linkage comprising a jaw-actuating lever, anadjustable link, and a jaw slidable on a converging way.

To provide for convergence of the jaws, and for the angular movement ofadjustable links 88. 98 with respect to levers 86, B1 and the jaws 33,34, suitable ball-and socket connections 92 have been provided betweeneach of said levers and each of said adjustable links and between eachof said links .and each of said jaws.

Approximately central of the length of the crank 82 on either side, andin the directions of oscillation thereof, are recessed, concave bearingportions or seats 83. substantially semi-cylindrical in form. On theupper extremities of jawactuating levers 86, 81 on either side, and inthe directions of oscillation thereof, are similar recessed, concavebearing portions 84, substantially semi-cylindrical in form and adaptedto lateral alignment with the corresponding bearing portions 83 on crank82. Crank 82, at the level of recessed bearing portions 93, has anaperture 85 extending therethrouzh in a direction substantiallytangential to the arc of rotation thereof. Extending through aperture95, in approximately the same plane as contains the quadriccrank linkageand normally perpendicular to crank 82, is adjustable tie-bolt 96threaded at either end, to receive adjusting nuts 81. Mounted preferablyon the forward end of the tie-bolt 96, in the direction of draw, isbearing member 98 engaging crank 82 and jaw-actuating levers 86. 81 inthe aforedescribed bearing portions 83 and 84, respectively. The saidbearing member 88, which is axially slidable on tie-bolt 86 andpositionable thereon by means of nuts 91, extends laterally across crank82 and across the jawactuating levers 86, 81, and is adapted to engagewith either of said jaw-actuating levers or said crank independently, orat times with all of them simultaneously. For engaging the oppositebearing portion of crank 82, or the opposite bearing portions injaw-actuating levers 86, 81, is a second bearing member 98 similarlymounted on said tie-bolt 96. The two bearing members 88 and 99 areprovided with semi-cylindrical or convex bearing surfaces adapted toengage in the aforesaid semi-cylindrical or concave bearing recesses ofthe crank and the levers.

The bearing member 98, slidable on tie-bolt 86, serves further as aspring seat for double-actin spring 88, which spring is mountedsurrounding the said tie-bolt 86 on that portion of the tie-bolt whichextends, to the left as viewed in Fig. 3, toward the jaw portion of thedraw head 38. An opposing spring seat I 88 is located at the end oftie-bolt 86 and is slidable thereon, being adjustable for position bymeans of adjusting nuts 91.

Levers 86, 81 and crank 82 are cooperatively related by means of theaforementioned doubleacting spring, tie-bolt, spring seats, and bearingmembers. The two-fold purpose of the spring and associated elements is,briefly, (1) to tend to keep levers and crank in the same axial line sothat they may function substantially as one split lever oscillatable onthe pin 19, and yet permit the levers to advance or retract relative toeach other in response to movement of the' crank, and in response to therelative positions assumed by the work-engaging jaws as they positivelyand separately engage the work; and (2) to store jaw-opening energy bycompression in the spring whereby the spring may effectuate movement ofthe levers to assist in the opening of the jaws, as will hereinafter bespecifically explained. Adjustabilities afforded in the various links,and the yieldability of the spring permit ready accommodation of theapparatus to work of varying size and shape.

For engaging the aforementioned latch 84, the pawl is pivotally mountedon pin I8I, fitted in suitable bearings I82 located in the base ofcarriage or draw head 38. A spring I83 connects pawl 85 and an anchoringpin I84, and tends to hold the pawl against either latch 84 (Fig. 3), orthe base of crank 82 under the said latch. For moving said pawl from itslatched position under latch 84, a.longitudinally-extending trip rod I85is mounted in bearings I86 on top plate 18 of carriage 38. The said triprod is adjustable for length, as indicated in the drawing, and is somounted upon the carriage as to contact die head 3 as the carriageapproaches said die head. Upon contacting die head 3, trip rod I85 movesagainst pawl 85, thereby unlatching crank 82 and allowing movement ofthe said quadric-crank linkage to take place.

The operation of the carriage will not be enlarged upon since it will befound fully set forth in our application, Serial No. 341,696,abovementioned. 1

Mandrel section of the bench located on the stock feeding side of thedie head 3, are a plurality of mandrel-supporting members 24.

Operation Assuming a tube on a mandrel rod in the loading position, thecarriage30 on the tracks 3| at some distance from the die head 3, andthe draw chain moving, such as would be the case following completion ofa previous drawing operation, a cycle of operations may be instituted bythe closing of a control switch (not shown) adapted to initiallyenergize the return chain operating motor 82.

Upon energization of the carriage return motor 62' movement of thecarriage 33 toward the die head 3 will begin. The limit switch dog 39 oncarriage 38 will first strike the limit switch 45 which, because of theprevious closing of limit switch 44, will cause means not shown to indexthe mandrels to present a tube opposite the die.

At a position along the main frame of the draw bench nearer the die head3, the limit switch dog 33 on the carriage 30 engages and operates limitswitch 48. Upon the movement of limit switch 40, the field control ofthe return drive motor 52 is, in the operation here described, modifiedto bring the return speed of the carriage to a substantially constantbase value.

At a position along the main frame of the draw bench still nearer thedie head, the said limit switch dog 38 engages and operates limit switch44. Upon the movement of limit switch 44, means not shown are adapted topush the mandrel into the die. At this position the pointed end 9 of thetube extends through die 4 for engagement by the jaws 33 and 34 of thedrawing carriage 33.

Upon further approach of the carriage 30 to the die head the limitswitch dog 39 strikes and actuates successive limit switches 4|, 43, and42, which in that order respectively decrease the speed of the returndrive motor 62 by armature shunt control, decrease the speed of the drawchain 36 to a pre-set initial drawing speed, and stop the motion of thedrawing carriage as it approaches the die head by applying dynamicbraking through the drive motor 52.

As carriage 30 comes to rest at die head 3, trip rod )5 contacts the diehead and releases pawl 85 irom under latch 84, whereupon hook 35 fallsinto and engages its arcuate portion 16 with a link of chain 36. Thefalling motion of the hook 35 imparts a closing movement to the jaws 33,34 as described above, whereupon the Jaws engage and grip the pointedend 3 of a properly positioned tube 3.

The draw chain 36 may be moving at a slow speed or stopped as controlledby thalimit switch 43. It stopped the draw chain would then be startedby a manually actuated switch or other device (not shown). Assuming thatit is movingat a slow speed as here provided, immediately upon theengagement of the hook 35 with the draw chain, the carriage 38 beginsits travel away from the die head and the drawing of the tube begins.Drawing tension through the chain, hook,

carriage, jaws, tube, mandrel rod bulb, and man- 5 drel rod raises thehook 35 to its normal position, where crank 82 is latched by pawl 85,clamps the jaws 33 and 34 upon the po'intedend' 3 of the tube 8, andbrings the mandrel rod bulb ll into final registry with the die 4.

Before continuing with the description of the operation, it may bepointed'out that if the laws should fail to engage the end of the tubethere will be no tension on the chain 36 and the hook 35 will not besubstantially raised. Rather than permit the carriage 33 to travel outthe full length 01' the frame, means for stopping the carriage andreturning it again to the die head are provided. The roller follower 12of hook release lever II will strike the cam 65, which will raise thehook release lever and will release the hook from the chain, whereuponthe carriage 38 may have a short return travel back to the die head tore engage tube 8.

Assuming, however, that the jaws have engaged the end of the tube uponthe falling of book 35 into the draw chain, the motion 01' the carriageoutward under drawing tension will continue as first described. The hookwill be raised and latched by the tension on the chain, but the lawswill remain closed under the force exerted by the work tending to drawthem into tighter engagement therewith despite the fact that compressionof spring 88 aioredescribed will also tend to open the same. I,

The limit switch dog 33 on the carriage 36 will firstactuate and engagelimit switch 42, resetting the same and electrically disconnecting fromcircuit the return drive motor 52 so that the return chains 3'! and 38,fixedly connected to the carriage, may cause reverse rotation of thedrive motor 62 against no electromagnetic forces.

The limit switch dog 36 will next reset the limit switch 43 and causeacceleration of the drive chain 36 from its initial slow speed to normal45 drawing speed.

The next limit switch 4| will be merely reset without eflect upon thecycle of operations.

Likewise the next limit switch 44 will be reset, to its first position,causing means not shown to become operative for tending to withdraw amandrel rod, e. g. [8, and bulb, e. g. H, from registry with die 4. Thistendency, however, will remain ineffective while there is drawing"tension on a tube 8, but will be adapted to withdraw the mandrel rod andbulg upon completion of the drawing operation.

The next limit switch 40 will be merely reset without eflect upon thecycle of operations.

The final limit switch 45 will be reset to an an ineffective positionwithout affecting the cycle 01' operations, whereupon the electric andpneumatic control system will be then in condition W for operation asdescribed at the beginning of this drawing cycle.

After passing these limit switches, preferably located within a distancefrom the die head corresponding to the minimum length oi tubeto behandled, the carriage 38 will continue to be drawn out along tracks 3!on main frame I by draw chain 35 until tube 8 is drawn-completelythrough die 4. When tube 8 makes it exit from die 4, there will be animmediate release of drawing tension throughout the draw bench: and therecoiling eflect of the tube 8 in connection with 15 the stored energyin the spring 88-will immediately open the Jaws 33 and 34 or carriage30, whereupon thetube 8 will be released and allowed to fall onto anysuitable unloading devices arranged therebeneath (not shown). At thesame time the release of tension in the draw chain 36 will permit thechain to fall from engagement with the hook 35 and the carriage willcome to rest, Also the pressure or air against the piston in themanipulating mechanism, will then be eiiective to move the mandrel rodand bulb out of registry with die I and to retract the same into andwithin its protective tubular shell It.

It will also be apparent from the foregoing description that thisapparatus is adapted to the drawing of rods and bars not necessitatingthe use of mandrel rods and bulbs, upon the provision of a push rod inplace or each, mandrel rod, which push rod would be adapted to advancethe work into registry with the die. modification a fixed mandrel couldbe employed for drawing substantially hollow shapes.

It should be understood that many or the auxiliary devices with whichthis draw bench has been described are not essential to its usefuloperation, and that many other combinations and relations of the partsand associated devices may be employed without departing from the natureand scope of this invention as defined in the appended claim.

What is claimed is:

In a draw bench, a die, a bench irame extending from said die, a drawhead movable on said frame toward and away from said die, a continuousdrawing member, attaching means on said draw head for engagement withsaid drawing member and adapted to be raised thereby under drawingtension, means for locking said attaching means in raised position,means associated with said locking means adapted to release the same asthe draw head reaches the die,

Also, in a similar whereby the attaching means is freed to engage thedrawing member, thereby to initiate a drawing operation, an armassociated with said attaching means for raising the same when notlifted by said drawing member, said arm being disposed at one side ofsaid draw head, a cam means on said frame near said :iie'ior engagementby said arm only when there is no load on said drawing member, said armnormally clearing said cam means when said attaching means is raisedunder drawing, tension, and cam means on said frame near the end thereofopposite said die for engagement by said arm to disengage said attachingmeans from said drawing member if said draw head should be moved theretoby said drawing member, said attaching means being raised into positionto be held by the locking means when said arm is actuated by engagementwith either of the cam means.

' RAYNAL W. ANDREWS. Ja.

ARTHUR T. DEILY.

aernaancas crrnn The following references are oi record in the tile ofthis patent:

UNITED STATES PATENTS Number Name Date 1,496,125 Larson June 3, 1924-1,568,'793 Atkins Jan. 5, 1926 1,951,073 Wallis Mar. 13, 1934 1,541,424Linderme June 9, 1925 2,196,646 Smith Apr. 9, 1940 FOREIGN PATENTSNumber .Country Date 451,481 British Aug. 6, 1936 798,144 French May 9,1936 4,622 French Sept. 2, 1905 489,388 British July 26, 198B

